Those should seem pretty relevant but, 3, and 4, are for memory (RAM) testing purposes. 5, 6, and 7 are the windows partitions, that are setup on your machine,
I would guess that one of the three is the actual boot partition, one is a backup partition, and the third one, is the actual OS itself. While number 7 seems a bit off in the name, (unless you have vista installed as well) but it is probably just a mistake that grub made when it tried to determine what is on the partitions and give them names.
You could correct/change them if you wanted to, ( if I were you, I would leave them alone) but if everything is working fine there really is no need to.
Further if you don't want to see options 3 or 4 you could remove them. Again there really is no benefit other than perhaps saving some screen space. But even that is silly compared to messing around with the grub config, and ruining something.